This invention relates to electrical circuits and more specifically to a power supply designed for the use with durable, long lifespan components while having acceptable power factor.
For alternating current (AC) distribution of electrical power, power factor is the ratio of the real power flowing to a load, to the apparent power in the circuit, and is a dimensionless number between −1 and 1. Real power is the capacity of the circuit for performing work in a particular time. Apparent power is the product of the current and voltage of the circuit.
Due to energy stored in the load and returned to the source, or due to a nonlinear load that distorts the wave shape of the current drawn from the source, the apparent power will be greater than the real power. A negative power factor occurs when the device which is normally the load generates power which then flows back towards the device which is normally considered the generator.
A high power factor is generally desirable in a transmission system to reduce transmission losses and improve voltage regulation at the load. It is often desirable to adjust the power factor of a system to near 1.0. When reactive elements supply or absorb reactive power near the load, the apparent power is reduced. Power factor correction may be applied by an electric power transmission utility to improve the stability and efficiency of the transmission network. Individual electrical customers who are charged by their utility for low power factor may install correction equipment to reduce those costs.
Therefore, there is a need for improved power factor correction circuitry that brings the power factor of an AC power circuit closer to 1 by supplying reactive power of opposite sign.